08 December 2016

Online furniture seller Wayfair and Niantic's Pokémon
GO have more in common than you might think. Both of these companies
use augmented reality to create innovative, immersive experiences for their
users. I sat down with Mike Festa, Director of Wayfair Next, and Tatsuo Nomura,
Product Manager for Pokémon GO, at our recent Playtime event to discuss how
developers can make the most of AR as a platform.

From 3D furniture modelling in WayfairView
using Tango, to logging
countless miles catching Pokémon, hear how these developers are innovating with
AR, and get their advice for others looking to use AR in their apps and games.

Check
out more sessions from our global Playtime events to learn best practices
for your app and game businesses. Also, stay up to date with more videos from
events, product news, and tips to help grow your business on Google Play with
the Playbook for Developers app.

07 December 2016

We’re wrapping up our annual global Playtime series of events with a last stop in Tokyo, Japan. This year Google Play hosted events in 10 cities: London, Paris, Berlin, Hong Kong, Singapore, Gurgaon, San Francisco, Sao Paulo, Seoul and Tokyo. We met with app and game developers from around the world to discuss how to build successful businesses on Google Play, share experiences, give feedback, collaborate, and get inspired.
You can now watch some of the best Playtime sessions on our Android Developers YouTube Channel, as listed below. The playlist opens with a video that celebrates collaboration.

Learn how we're helping users discover apps in the right context, creating new
ways to engage with users beyond the install, and powering innovative
experiences on emerging platforms like virtual reality, wearables, and auto.

Android development is more powerful and efficient than ever before. Android
Studio brings you speed, smarts, and support for Android Nougat. The broad range
of cross-platform tools on Firecase can improve your app on Android and beyond.
Material Design and Vulkan continue to improve the user experience and increase
engagement.

Daydream View is a VR headset and controller by Google that lets people explore
new worlds, or play games that put them at the center of action. Learn how we're
helping users discover apps in the right context and powering new experiences
with Daydream and Tango.

Augmented reality engages and delights people everywhere. In this fireside chat,
online furniture seller Wayfair and Niantic's Pokémon
GO share their experiences with AR and discuss how other developers can make
the most of the platform.

Learn how to create apps and games for emerging markets, which are expected to
drive 80% of global smartphone growth by 2020, by recognizing the key challenges
and designing the right app experiences to overcome them.

Planning and executing a great growth strategy involves a complex set of choices
and mastery of many tools. In this session we discuss topics including key
business objectives, tools, and techniques to help you solve the growth puzzle
with our partner, SoundCloud.

User growth isn't just about growing the number of users you have. The key to
sustainability is creating and delivering core product value. In this session,
VC Greylock discusses how to identify your core action to focus on and shows you
how to use these insights to optimize your app for long term growth.

As the app marketplace becomes more competitive, developer success depends on
retaining users in apps they love. Find out which Google tools and features can
help you analyze your users' behaviors, improve engagement and retention in your
app and hear insights from others developers including Lifesum.

Learn about Google's efforts to enable users, around the world, to seamlessly
and safely pay for content. This session provides updates on Google Play billing
and recent enhancements to our subscriptions platform.

Customize your game's experience for different users by targeting them with lifetime value
models and predictive analytics. Hear how these concepts are applied by
Space Ape Games to improve retention and monetization of their titles.

Learn how successful developers keep their games fresh and engaging with Live
Operations. In this talk, the LiveOps expert on Marvel: Contest of Champions
discusses tips about the art and science of running an engaging LiveOps event.

Family-based households with children have higher tablet and smartphone
ownership rates than the general population. These families are more likely to
make purchases on their mobile devices and play games. Learn about how parents
choose what to download and buy, and how you can prepare for maximum conversion.

PlayKids has been at the forefront of the subscription business model since
their inception. See how they best serve their subscribers by refreshing their
content, expanding their offerings and investing in new verticals.

06 December 2016

Android users are downloading tens of billions of apps and games on Google Play.
We're also seeing developers update their apps frequently in order to provide
users with great content, improve security, and enhance the overall user
experience. It takes a lot of data to download these updates and we know users
care about how much data their devices are using. Earlier this year, we
announced that we started using the
bsdiff algorithm(by
Colin Percival). Using bsdiff, we were able to reduce the size of app
updates on average by 47% compared to the full APK size.

Today, we're excited to share a new approach that goes further — File-by-File
patching.App Updates using File-by-File patching are, on average,65% smaller than the full app, and in some cases more than 90%
smaller.

The savings, compared to our previous approach, add up to 6 petabytes of user
data saved per day!

In order to get the new version of the app, Google Play sends your device a
patch that describes the differences between the old and new versions
of the app.

Imagine you are an author of a book about to be published, and wish to change a
single sentence - it's much easier to tell the editor which sentence to change
and what to change, rather than send an entirely new book. In the same way,
patches are much smaller and much faster to download than the entire APK.

Techniques used in File-by-File
patching

Android apps are packaged as APKs, which are ZIP files with special conventions.
Most of the content within the ZIP files (and APKs) is compressed using a
technology called Deflate.
Deflate is really good at compressing data but it has a drawback: it makes
identifying changes in the original (uncompressed) content really hard. Even a
tiny change to the original content (like changing one word in a book) can make
the compressed output of deflate look completely different. Describing
the differences between the original content is easy, but describing
the differences between the compressed content is so hard that it leads
to inefficient patches.

Watch how much the compressed text on the right side changes from a one-letter
change in the uncompressed text on the left:

File-by-File therefore is based on detecting changes in the uncompressed data.
To generate a patch, we first decompress both old and new files before computing
the delta (we still use bsdiff here). Then to apply the patch, we decompress the
old file, apply the delta to the uncompressed content and then recompress the
new file. In doing so, we need to make sure that the APK on your device is a
perfect match, byte for byte, to the one on the Play Store (see APK Signature
Schema v2 for why).

When recompressing the new file, we hit two complications. First, Deflate has a
number of settings that affect output; and we don't know which settings were
used in the first place. Second, many versions of deflate exist and we need to
know whether the version on your device is suitable.

Fortunately, after analysis of the apps on the Play Store, we've discovered that
recent and compatible versions of deflate based on zlib (the most popular
deflate library) account for almost all deflated content in the Play Store. In
addition, the default settings (level=6) and maximum compression settings
(level=9) are the only settings we encountered in practice.

Knowing this, we can detect and reproduce the original deflate settings. This
makes it possible to uncompress the data, apply a patch, and then recompress the
data back to exactly the same bytes as originally uploaded.

However, there is one trade off; extra processing power is needed on the device.
On modern devices (e.g. from 2015), recompression can take a little over a
second per megabyte and on older or less powerful devices it can be longer.
Analysis so far shows that, on average, if the patch size is halved then the
time spent applying the patch (which for File-by-File includes recompression) is
doubled.

For now, we are limiting the use of this new patching technology to auto-updates
only, i.e. the updates that take place in the background, usually at night when
your phone is plugged into power and you're not likely to be using it. This
ensures that users won't have to wait any longer than usual for an update to
finish when manually updating an app.

Disclaimer: if you see different patch sizes when you press "update"
manually, that is because we are not currently using File-by-file for
interactive updates, only those done in the background.

Saving data and making our
users (& developers!) happy

These changes are designed to ensure our community of over a billion Android
users use as little data as possible for regular app updates. The best thing is
that as a developer you don't need to do anything. You get these reductions to
your update size for free!

If you'd like to know more about File-by-File patching, including the technical
details, head over to the Archive Patcher GitHub
project where you can find information, including the source code. Yes,
File-by-File patching is completely open-source!

05 December 2016

Today we're rolling out an update to Nougat -- Android 7.1.1 for Pixel and Pixel
XL devices and the full lineup of supported Nexus devices. We're also pushing
the Android 7.1.1 source code to the Android Open Source Project (AOSP) so
that device makers can get their hands on the latest version of Android.

With Android 7.1.1 officially on it's way to users, it's a good time to make
sure your apps are ready.

What's in Android 7.1.1?

Android 7.1.1 is an incremental release that builds on the features already
available on Pixel and Pixel XL devices, adding a handful of new features for
consumers as well as optimizations and bug fixes on top of the base Android 7.1
platform (API level 25).

Coming to consumer devices soon

We're starting the Android 7.1.1 rollout today, and we expect it to reach all
eligible devices over the next several weeks. Pixel and Pixel XL devices will
get the over-the-air (OTA) update, as will Nexus 5X, Nexus 6P, Nexus 6, Nexus 9,
Nexus Player, Pixel C, and General Mobile 4G (Android One) devices. Devices
enrolled in the Android Beta
Program will receive the final version as well. As always, you can also
download and flash this
update manually.

We've also been working with our device manufacturer partners to bring Android 7.1.1
to their devices in the months ahead.

Make sure your apps are ready

Take this opportunity to test your apps for compatibility and optimize them to
look their best on Android 7.1.1, such as by providing round
icons and adding app shortcuts.
We recommend compiling your app with, and ideally targeting, API 25. See our recent
post for details.

With the final platform we’re updating the platform and build tools in Android Studio, as well as the
API Level 25 emulator system images. The latest
version of the support library (25.0.1)
is also available for you to add
image keyboard support, bottom
navigation, and other features for devices running API Level 25 or earlier.

We're also providing downloadable factory and OTA images on the Nexus Images page to
help you do final testing on your Pixel and Nexus devices. To help scale your
testing, make sure to take advantage of Firebase
Test Lab for Android and run your tests in the cloud at no charge through
the end of December.

What's next?

We'll soon be closing open bugs logged against Developer Preview builds, but
please keep the feedback coming! If you still see an issue that you filed in the
preview tracker, just file a new issue
against Android 7.1 in the AOSP issue tracker. You can also continue to give us
feedback or ask questions in the developer community.

As mentioned
back in August, we've moved Android Nougat into a regular maintenance cycle
and we're already started work on refinements and bug fixes for the next
incremental update. If you have an eligible device that's currently enrolled in
the Android Beta Program, your
device will automatically receive preview updates of upcoming Android Nougat
releases as soon as they are available. If you don't want to receive those
updates, just visit the Beta
site and unenroll the device.

Thanks for being part of the developer preview. Let us know how this year's
preview met your needs by taking a short
survey. Your feedback helps to shape our future releases.

30 November 2016

As one of our most popular Udacity courses, the Developing Android Apps
course was recently updated to ensure developers have the resources to build
high quality apps. This course, which has already helped more than half a
million developers learn to build Android apps, has been through the car wash
and come out sparkling clean and updated.

Google and Udacity have worked together to update the course to include the very
latest changes in Android and Android Studio, including how to use the new
Constraint Layout editor, and how to use Firebase Job Dispatcher. Learn best
practices for building Android apps using Android 7.0 (Nougat) while keeping
your apps backwards compatible in older versions, learning at your own pace in
your own time.

You sent us feedback that some of the lessons were a little difficult to get
through, so we've restructured the lessons and added smaller apps for you to
build as you progress through the course. So not only will you build the
Sunshine weather app as a complete, integrated application that spans the entire
course, but you'll also create an app in each lesson to help you learn
individual concepts.

Build a To Do app and add new tasks as you learn how to build a ContentProvider.

This course brings back Android experts Dan Galpin and Reto Meier from Google, and Lyla Fujiwara from Udacity, and introduces new faces from Google and Udacity.

This updated course teaches the skills that are tested by the Associate Android
Developer certification exam. Udacity is offering a package that combines the
updated Developing Android Apps course with a voucher for the Associate Android
Developer certification exam. If you pass this exam, you will earn the Associate
Android Developer Certification and show that you are competent and skilled in
tasks that an entry-level Android developer typically performs. Enroll in
Udacity's Fast
Track to get prepared and take the Associate Android developer exam at: https://www.udacity.com/course/nd818.

Posted byTamzin Taylor, Partner Development Manager at Google
Play, & Kristina Narusk, Head of Production at Memrise

Getting people to install your app is one thing, getting them to sign up to your
paid offering is quite another. It's important to understand the complete
journey your users take from installing your app to paying for something. Once
you do, you can experiment on the flow to try and increase conversions. Memrise
has found great success in experimenting on their language learning app to
increase the number of paying users.

Four experiments Memrise use to improve conversions

Memrise
makes languages fun with a number of different learning modes you can play to
help increase your vocabulary in a chosen language. You can download the app for
free and play some of the modes or take advantage of their premium subscription
offering called 'Memrise Pro' which offers new game modes and additional
features like offline learning. Memrise recently ran a number of conversion
experiments with the main objective of increasing the Average Revenue Per Daily
Active User (ARPDAU). These experiments tested multiple user experience and
pricing experiment scenarios.

What they did: Memrise wanted to know what motivation and call
to action would convert the most users to buy a Pro subscription from a locked
game mode in the app. To do this, they ran an A/B test with two similar designs,
featuring different reasons for the user to upgrade, and compared the results to
their original upgrade messaging.

Test A: Focus on ‘difficult’ words with an orange background.

Test B: Focus on ‘favorite’ words with a pink background.

Results: Test A performed the best. Conversion to Pro in Test A
was 28% higher than in Test B. Pro mode usage was subsequently 9.7% higher in
Test A compared to Test B too.

Next steps: After seeing how test A won the experiment, Memrise
applied this creative across the board. Subscribers driven by that particular
mode increased as a percentage of all subscriptions in the app by 16%. Memrise
plans to run additional A/B tests at others points of conversion in the app to
see if they can increase the results even further. They'll also try different
text for the call to actions.

In 2015, Google Play launched new minimum local price levels in countries around
the world. To take advantage of the new price points, Memrise tested lowering
localised prices in certain markets to better match purchasing power. Prices
were an average of 6 times lower during this experiment.

Results: After 30 days, Memrise saw the following changes in
conversions to paid users:

🇹🇷

Turkey

⇧180%

🇧🇷

Brazil

⇧182%

🇷🇺

Russia

⇧99%

🇲🇽

Mexico

⇧115%

🇮🇳

India

⇩5.1%

🇮🇩

Indonesia

⇧152%

🇰🇷

South Korea

⇧120%

🇹🇭

Thailand

⇧70%

🇲🇾

Malaysia

⇧27%

Next steps: The change in price affected the subscription
dynamics with more users taking advantage of Memrise's in-app discounted offer
in most countries. The offer was for annual subscribers only and has led to a
positive effect on LTV. One insight from the experiment was that Indian users
prefered to have the option to subscribe in weekly or monthly increments and not
just annually. Memrise is still tracking carefully to see whether the discounted
subscription pricing will lead to an increase in conversions.

3. Test when and how often you offer free trials to see if that affects
conversion rate

Memrise occasionally offers users, who aren't Pro subscribers, a free trial of
one of the Pro game modes while cycling through the various free modes. After
the free trial session, users are presented with an offer to subscribe. Memrise
experimented with the offer's timing making it appear more frequently while
users were cycling through normal free sessions Instead of after every 49th
session, users saw the unlocked mode after every 21st session.

An example of a free trial of a Pro mode.

After completing a free trial, users see a discounted subscription offer.

Results: Offering a free trial more frequently paid off. The
conversion rate increased by 50% while all other conversion rates remained the
same.

Next steps: Memrise maintained the more frequent offer cadence
and has seen revenue growth as a result.

4. Test whether seasonal discounts result in more conversions
Memrise launched a 'Back to School' campaign presenting all users with a
discounted annual plan offer for a week in September 2016. The aim was to
convert more users and generate higher value users from annual subscription
plans.

Results: Memrise saw two effects from the seasonal offer. As a
result of only presenting an annual period and removing weekly and monthly, 20%
fewer users per day converted to Pro. However, because more people were taking
an annual subscription than a shorter subscription, the average revenue per day
increased by 32% justifying the change.

Next steps: Memrise plans to test different offers in the
future with a combination of subscription offerings. They'll also focus offers
in countries like Turkey and Mexico, where they saw the biggest increase in
conversions.

Keep experimenting and take advantage of new features to improve the
user experience and increase conversions

At Playtime San Francisco, we
announced that introductory pricing for subscriptions would be coming soon
and the feature is now live. By continually testing messaging, pricing, offers,
and free trials or discounted trials, you could increase the conversions in your
app and your ongoing revenue just like Memrise. Learn more about Google
Play in-app billing subscriptions and get
the Playbook for Developers app to stay up-to-date with features and best
practices that will help you grow a successful business on Google Play.